Automatic control for a self-propelled carriage to enable one-man cable yarding

We have developed an automatic control scheme for a self-propelled carriage to facilitate cable yarding by a single choker setter. Automating techniques are divided roughly into “automatic traveling” and “automatic unloading” techniques. For achieving automatic carriage motion and for making the carriage stop at a target location, we constructed a prototype odometer system to measure the distance traveled and developed methods to reduce the measured error. A corroborative experiment in which logging was done six times was conducted, and for an average logging distance of 228 m, the maximum deviation from the target location was found to be 0.22 m. In the case of automatic unloading, we measured the hydraulic motor pressure of the hoisting winch drive and designed a technique for detecting when the load suspended from a hoisting cable becomes a “no load.” By using this method, automatic unloading from a suspension height of 10 m was done accurately by using an automatic unloading hook when a load was heavier than 100 kg